Apparatus for continuous soapmaking



Sept. 1 6, 1958 F. T. PALMQvlsT APPARATUS FOR CONTINUOUS soAPMAKING 3Sheets-Sheet 1 Original Filed Jan. 2, 1951 Sept. 16, 1958 F. T.PALMQvlsT APPARATUS FOR CONTINUOUS SOAPMAKING 3 Shets-Sheet 2 OriginalFiled Jan. 2, 1951 I, IIJ

INVENTOR. Fredrik 7oa'or Pa/rn BY gvs @m2, .Wwf

ATT o RNEYS F. T. PALMQvlsT APPARATUS FOR CONTINUOUS SOAPMAKING Sept.16, 1958 3 Sheets-Sheet I5 Original Filed Jan. 2, 1951 u QM J n NN fil..

IN VEN TOR. Fredrik @oder Palm www 'J' Ajr'roRNEYS United States PatentO APPARATUS FR CGNTINUOUS SOAPMAKING Fredrik Teodor Palmqvist,Stockholm,

to Aktiebolaget Separator, poration of Sweden Sweden, assignorStockholm, Sweden, a cor- This invention relates to apparatus for thecontinuous manufacture of soap, in which the material is subjected to aseries of successive operations. The present application is a divisionof my copending `application Serial No. 203,840, filed January 2, 1951,now Patent No. 2,727,915.

The manufacture of soap in a continuous process is not novel in itself,but apparatus heretofore devised for this purpose have certaininconveniences, which it is an object of the present invention toovercome.

In the conventional manufacture of soap, the procedure is briey vasfollows: Fat and lye are saponiiied, and the product obtained is grainedout with a salt solution, usually common salt, whereupon the neat soapthus formed is separated from the spent lye and then washed, in afitting stage, with lye and salt solution, a purified soap thereby beingobtained after removal .of the new spent lye or the niger. i

The apparatus of the present invention differs from prior apparatus inregard to the manner in which it carries out the various stages.

It is known that when saponifying fat with lye the reaction at iirsttakes place slowly, until a certain amount of fat has been saponiied,and then suddenly proceeds at a very high rate which then diminishes.Thus, the time-saponification curve is similar to an S. This fact isutilized in the present invention.

A characterizing feature of the present invention is that, aftercontinuity of operation has been reached, the apparatus maintainssaponitied fat in continuous circulation in a separate circuit in thefirst or saponiiication stage, and means are provided for adding lye ata suitable point of the circuit in order to saponify non-saponiiied fat(if any) and fat di'icult to saponify, as well as fat fed to thiscircuit. The lye and fat are continuously added in xed proportions andthoroughly mixed or atomized in the circulating material, and means areprovided for continuously withdrawing 4a quantity of saponiied fat(corresponding to the added quantity) from the circuit and feeding it tothe next stage.

Another feature of the invention is that the grainingout stage followingthe saponifying stage is fully separated from the latter and likewiseprovided with a circuit to which predetermined amounts of a saltsolution are continuously fed while a portion of the circulatingmaterial is continuously withdrawn. This withdrawn material is led intoa centrifugal separator where it is separated into a stream of neatsoap, which is fed to the subsequent iitting stage, and a stream .ofspent lye containing traces of soap together with glycerol, salts andorganic compounds, which are withdrawn from the process.

A third feature is that the neat soap is washed in one or several(usually two) successive fitting stages, each of which is preferablyprovided with a circuit to which neat soap, lye and salt solution arefed and from which a stream of the material is continuously withdrawninto and separated in a centrifugal separator. When two consecutivefitting stages are used, the neat soap from the separator of the rsttting stage is fed, together with lye, salt solution and water, to thecircuit of the second fitting stage, and the niger discharged from theseparator of the second tting stage and consisting of lye, saltsolution, soap and water is returned to and used in the circuit of thefirst fitting stage. Y

A fourth feature is that the saponifying and graining stages and, ifrequired, the fitting stage or stages may be carried out in the presentapparatus at super-atmospheric pressure, which makes it possible to usea raised temperature. The effect of the raised temperature is to shortenthe saponifying time, to lower the viscosity of the material, resultingin increased throughput of the separators, and to reduce the watercontent of the grainedout soap, which facilitates the subsequent fittingor pitching operation. When the saponifying stage is effected atelevated pressure and elevated temperature, this part of theinstallation can be made smaller owing to its increased capacity. Whenthe saponifying and graining stages, and possibly the litting stage orstages, are effected at elevated pressure, an advantage is obtained inthat the dosing or metering devices used for the supply of fat and lye(and, if required, salt solutions and water) to the circuits of thevarious stages, may be made as propelling devices for passing the soapmass through the whole or a part of the system, in which case theypreferably consist of piston pumps. One or several of the pumpsotherwise required in the pipes to the separators may then beeliminated. When elevated pressure is used, the separators should be ofthe air-tight or closed type.

For a better understanding of the invention reference may be had to thefollowing description in conjunction with the accompanying drawings, inwhich Figs. l, 2 and 3 are diagrammatic views of three different formsof the new apparatus Vadapted for use in practicing the method of theinvention.

In Fig. 1 I have illustrated a saponifying stage, a graining stage, andtwo fitting stages. The last fitting stage is not always necessary andmay be eliminated.

The apparatus of the saponiiication stage comprises a tank or holdingzone 1, a circulation pump 2, a tank or holding zone 3, a mixer 4, and aheater 5, communicating with one another through pipes 6, 7, S, 9, 10and 11, and forming together the circuit of the saponifying stage. Thefat to be saponiiied is supplied through a fat feed line 12 and the lyethrough a lye feed line 13. ln continuous operation, part of thematerial is withdrawn through pipe 14 to the next stage. The fat isgenerally in fluid form and the lye, usually sodium lye, is relativelystrong. Before starting the plant, the pipe 14 is preferably closed by avalve 14a, whereupon fat and lye in accurately controlled amounts arecontinuously fed into the circuit through pipes 12 and 13, as bymetering or dosing devices such as piston pumps, and are circulated bythe pump 2. The mixture is heated in passing through the heater 5, whichmay ibe of any conventional type. The temperature should be sufficientlyhigh to allow the soap to be pumped, but it may exceed C. When thesaponitication takes place at a temperature higher than 100 C., theapparatus must be constructed to withstand the generated high pressure.After a period of feeding and circulation, with valve 14a closed, thetank 1 will be filled to a certain level and contain mainly saponiedfat.

The valve 14a is then opened and a stream containing a minor portion ofthe saponied fat is led through pipe 14, the major portion continuing topass through the circuit while lye and fat are added thereto in fixedproportions. The lye added in front of the pump 2 saponities anyresidual fat yor fat diicult to saponify in the stream arriving fromtank 1, the pump eiecting a good mixing action so that the lye reactswith the soap in tank 3 to form an alkaline soap emulsion, to which fatis then added through pipe 12. Because the alkaline soap emulsionalready contains a completely saponiiied fat when the addition of fat ismade through pipe 12, the saponification of the added fat takes placemore rapidly than if no soap were present. The saponificati-on isfacilitated by passing the material through the mixer or mixing zone 4,which produces an emulsion of fat and alkaline soap, and by the heatingin the heating zone 5. As the saponifying reaction is exothermic, theheater 5 may, if required, be turned olf during continuous operation.The soap discharging in continuous operation from tank 1 has beenpractically completely saponified therein. Owing to the continuouscirculation in the saponifying circuit, it is possible to add the fatand lye through dosing or metering devices in the form of piston pumps,whereby they become evenly distributed in the mass by the circulation.The tank 1 has a small diameter in relation to its height, for thepurpose of making the mass pass evenly through it.

The apparatus of the graining stage comprises a circulation pump 15, atank i6, and communication pipes 17, 18 and 19, all of which form thecircuit of the graining stage. This stage also comprises a 'feed pump20, a centrifugal separator 21, pipes 22, 23, 24, 25 and also a pipe 26.Saponitied material from the saponifying stage is fed to the circuit ofthe graining stage through the pipe 14, and a salt solution, generallycontaining ordinary salt, is added through pipe 26 from a dosing ormetering device (not shown). Owing to the circulation in the grainingcircuit, a piston pump may also be used to advantage here as dosingdevice. The mixture is circulated through the graining circuit -by thepump 15, and a part is discharged to the separator 21 through the pipe22. The added salt solution should be of optimum quantity andconcentration. After the material has passed through the separator 21,neat soap is obtained as one of the separated components in dischargepipe 25 and is led to the fitting sta-ge or stages. The other separatedcomponent, comprising glycerol, small amounts of soap, salts andpossibly organic impurities, is discharged through pipe 2d and withdrawnfrom the process. If required, a heating device (not shown) maybearranged in pipe 17.

The rst fitting stage also includes a circuit, comprising a circulationpump 27, a heater 2S, a tank 29 and communication pipes Sii, 31, 32, 33,and also a feed pump 34, a centrifugal separator 35 and pipe lines 35,37, 3S, 39 and 4t). Neat soap is fed to this circuit through pipe 25,and lye and salt solution through pipe 4t). The mixture of thesematerials is pumped through the first fitting circuit by the pump 27 andis heated in the heater 28. Only a part of the circulating stream iswithdrawn through pipe 36 into the separator 35. Lye and salt solutionare preferably added through pipe ttl by a piston pump as the dosing ormetering device. Neat soap is discharged from the separator 35 throughthe pipe 39 and is further treated in the second fitting stage, if thereis any such stage. The other component separated in the centrifuge 35,which is niger consisting of a mixture of salts, soap and water, isdischarged through the pipe 38. These products may -be re-introducedinto the process, as will be described in the following.

The second fitting stage has also a circuit, comprising a circulationpump 41, a heater 42, a tank 43, and pipes 44, 45, 46, 47, and also afeed pump 48, a centrifugal separator 49, and pipes Sil, 51, 52, 53, 54.Neat soap is introduced into the circuit of the second fitting stagethrough pipe 39, and lye, salt solution and water through pipe 54, andare circulated by the pump while being heated in the heater 42. Only asmall portion of the circulating mixture is withdrawn through pipe 5t)and separated in the separator 49, from which soap mass dischargesthrough the pipe 53 while niger is discharged through pipe 52 and iseither withdrawn from the process through pipe 55 or reintroduced intothe circuit of the first tting stage through pipe 56. ln this case, too,it is advantageous to use a piston pump (not shown) as the dosing ormetering device for introducing lye, salt solution and water into thesystem through the pipe 54.

The niger discharging through pipe 3S in the first fitting stage mayadvantageously be reintroduced into the process, either wholly or inpart, depending upon its composition. If required, it may first bepurified in container 38a. Its alkali and salt contents may also beadjusted in container 38a by adding caustic soda, salt or water. Thesubstances may be introduced into the circuits of the saponifying orgraining-out stages, as indicated by dash lines in the drawings.

As compared with prior methods for continuous soapmaking, the inventionhas the advantage of giving a practically complete saponification in asingle stage, which is made possible because the niger is subjected tothe action of lye in great excess during one phase of the process in thecircuit. Another advantage is quick emulgation of the fat because it ispumped into niger. The saponication therefore starts on the steep partof the time-saponification curve, so that the saponification periodbecomes comparatively short. In other words, previously formed soap massis utilized to accelerate the saponication, which, so far as I am aware,is a new principle in this art. In addition, the power consumption islower than in most other processes for the same purpose, owing to thegood fat-emulgating properties of the niger. The saponification heat isutilized to obtain better thermal economy, which is novel in conjunctionwith the circulation through the circuit of the saponiication stage. Themethod also has the advantage of enabling a small total excess of lye,which means saving of lye as well as work and expense necessary toneutralize excess lye, all inconveniences inherent in other similarmethods. By using a circuit in one or more of the various stages, anyfluctuations in the dosing of substances added in the process areequalized, rendering it possible to use low speed piston pumps as dosingdevices, which is advantageous owing to their reliability. By usingholding tanks in the circuits, the circulating soap mass may be observedand supervised. Particular advantage is ascribed to the fact that theniger is grained-out in a separate stage, independent of the saponifyingstage, so that the graining operation does not interfere with thesaponification. This makes it possible to use the optimum quantity andconcentration of salt. The presence of salt in the saponifying stage maycause incomplete saponification. When the fitting is effected in twostages, the niger phase discharged at 52 from the second stage mayadvantageously be returned to the first fitting stage. The method alsohas the advantage that not more than two or three centrifugal separatorsare required, which is less than with other comparable processes. Thepumps 2, 15, 27 and 41 also serve as mixing devices.

The installation illustrated in Fig. 2 differs from that of Fig. l onlyin certain respects, and the same reference numerals have therefore beenused for corresponding parts in both illustrations. The differencesbetween the two installations are set forth below.

The installation of Fig. 2 is intended for operation at elevated orsuper-atmospheric pressure and, if required, elevated temperature in thesaponification and grainingout stages, whereas the fitting stages areeffected at atmospheric pressure. The numerals 60, 61 and 62 denotedosing pumps (for example, of the piston type) for feeding fat, lye andsalt solution into the pressure stages. Consequently, these pumps mustwork with elevated pressure, and they can advantageously be used forforcing the soap through the steps of the first two stages. The feedpump 20 illustrated in Fig. l can thus be dispensed with, which means asimplification of the installation. Fig. 2 shows a heater .63 in pipe 17and also shows a pump 64 (for example, a piston pump) which is necessaryto force the niger from pipe 38 into the pressure stages through thepipes 65'or 66, after adjustment of its concentration and, if required,purification. The dosing devices used for pipes 40 and 54 are not shown,as they may be of any conventional type.

The installation of Fig. 3 works entirely at elevated pressure. Althoughtwo fitting'stages are shown, one is sometimes sufficient. Thisinstallation differs only very little from that of Fig. 2, and thereference numerals used in Fig. 2 yapply in Fig. 3 for correspondingparts. The difference between Fig. 2 and Fig. 3 lies in the execution ofthe fitting stages. Between the graining stage and the first fittingstage, in Fig. 3, there is a tank 67 in which the pipes 25 and 4d and,if required, the pipe 56 end. The lye and the brine are preferablyintroduced by means of a dosing device 68 acting as a piston pump. Apipe 70 provided with a pump 69, preferably of the piston type, runsfrom the tank 67 to the circuit of the first fitting stage. Thisarrangement makes the pump 34 of Fig. 2 superfluous. Between the rst andthe second tting stage there is also a tank 71 in which the pipe 39 fromthe separator of the first fitting stage and the pipe 54 for supply oflye, brine and water end. The latter pipe is provided with a pump 72,preferably of the piston type, as a dosing device. A pipe 74, preferablyalso provided with a. pump 73 of the piston type, extends from the tank71 to the circuit of the second fitting stage. The feed pump 48 of Fig.2 may then be eliminated.

The embodiments illustrated and described as examples are shown onlydiagrammatically and for this reason various control valves desirable insuch apparatus have not been shown in the drawings.

It will be apparent that the circulation pump 2, holding tank 3, mixer 4and holding tank 1, are connected by piping 6-11 in series in a closedcircuit in the order mentioned, reckoned in the direction of flowthrough the circuit. Through this first circuit, the pump 2 circulatesaV quantity of the product of reaction of a first reactant introducedfrom feed line 13 at a point through which the circulating reactionproduct passes on its way from holding tank 1 to holding tank 3, and asecond reactant introduced from feed line 12 at a point through whichthe product passes on its Way from holding tank V3 to mixer 4. Thedischarge from this rst circuit is through line 14 from a point throughwhich part of the circulating reaction product passes on its way fromholding tank 1 to the first feed line 13. Thus, the first circuit servesto effect chemical reaction between the two reactants by continuouslycirculating a quantityof the reaction product through the closed circuitwhile adding the reactants at the respective specified points of thecircuit and at a rate corresponding to the rate of discharge of thereaction product through line 14.

I claim:

l. Apparatus for effecting chemical reaction between two reactants,which comprises parts includinga circulation pump, a rst holding tank, amixer, and a second holding tank, piping connecting all of said parts inseries in a closed first circuit in the order mentioned, reckoned in thedirection of flow of material through the circuit, a firstreactant feedline leading into the circuit at a point through which said materialflows on its way from the second tank to the first tank, a secondreactant feed line leading into the circuit at a point through whichsaid material ows on its way from the first tank to the mixer, and adischarge line leading from the circuit at a point through which saidmaterial passes on its way from the second holding tank to said firstreactant feed line.

2. Apparatusfor effecting chemical reaction between two reactants, whichcomprises parts including a circulation pump, a first holding tank, amixer, and a second holding tank, piping connecting all of said parts inseries in a closed first circuit in the order mentioned, reckoned in thedirection of flow of material through the circuit, a first reactant feedline leading into the circuit at a point through which said materialflows on its way from the second tank to the rst tank, a second reactantfeed line leading into the circuit at a point through which saidmaterial flows on its way from the first tank to the mixer, a dischargeline leading from the circuit at a point through which said materialpasses on its way from the second tank to said first reactant feed line,a second circuit including a third holding tank and a second circulatingpump communicating with the upper and lower portions of said third tank,a feed pipe leading from said discharge line of the first circuit intothe second circuit between said second pump and said lower portion ofthe third tank, a feed line leading into the second circuit between saidsecond pump and the lower portion of said third tank, a centrifugalseparator, and a discharge pipe from the second circuit leading to theseparator.

3. Apparatus according to claim 2, comprising also a feed pump. in saidlast discharge pipe.

4. Apparatus according to claim 2, comprising also a heater in saidsecond circuit.

5. Apparatus according to claim l, comprising also a graining circuitincluding a third holding tank and a second circulating pumpcommunicating with the upper and lower portions of said third tank, afeed pipe leading from said discharge line of the first circuit into thegraining circuit between said second pump and said lower portion of thethird tank, a salt solution feed line leading into the graining circuitbetween said second pump and said lower tank portion, a centrifugalseparator, a discharge pipe from the graining circuit leading to theseparator, said circuits, separator and interconnecting pipes forming aclosed system adapted for operation at superatmospheric pressure, anddosing devices connected to said feed lines for supplying the respectivefeeds therethrough and forcing soap through said system.

6. Apparatus according to claim l, comprising also a graining circuitincluding a third holding tank and a second circulating pumpcommunicating with the upper and lower portions of said third tank, afeed pipe leading from said discharge line of the first circuit into thegraining circuit between said second pump and said lower portion of thethird tank, a salt solution feed line leading into the graining circuitbetween said second pump and said lower tank portion, a centrifugalseparator, a discharge pipe from the graining circuit leading to theseparator,

a soap discharge pipe and an impurity discharge pipel leading from theseparator, a fitting circuit to which said last soap discharge pipeleads and including a circulation pump, a heater and a holding tankconnected in the order mentioned, reckoned in the direction of iiowthrough said fitting circuit, a lye and salt solution supply pipeconnected to the fitting circuit, said 'supply pipe and soap dischargepipe being connected to the fitting circuit between the holding tank andthe pump therein, a second centrifugal separator, and an interconnectingpipe leading to said last separator from the fitting circuit in front ofthe pump therein.

'7. Apparatus according to claim l, comprising also a graining circuitincluding a third holding tank and a second circulating pumpcommunicating with the upper and .lower portions of said third tank, afeed pipe leading from said discharge line of the first circuit into thegraining circuit between said second pump and said lower portion of thethird tank, a salt solution feed line leading into the graining circuitbetween said second pump and said lower tank portion, a centrifugalseparator, a. discharge pipe from the graining circuit leading to theseparator, a soap discharge pipe and an impurity discharge pipe leadingfrom the separator, a fitting circuit to which said last soap dischargepipe leads and including a circulation pump, a heater and a holding tankconnected in the order mentioned, reckoned in the direction of flowthrough said fitting circuit, a lye and salt solution supply pipeconnected to the fitting circuit, said supply pipe and soap dischargepipe being connected to the fitting circuit between the holding tank andthe pump therein, a second centrifugal separator, an interconnectingpipe leading to said last separator from the fitting circuit in front ofthe 7 pump therein, a pipe leading from said last separator fordischarge of fitted soap, a second fitting circuit including acirculation pump, a heater and a holding tank connected in the ordermentioned, reckoned in the direction of fiow therethrough, a supply pipefor feeding lye, salt solution 5 and water into the second ttingcircuit, said last supply pipe and fitted soap discharge pipe beingconnected to the second fitting circuit between the holding tank and thepump therein, a third centrifugal separator, and an interconnecting pipeleading to the third separator from the l second fitting circuit betweenthe tank and pump thereof lbut in front of said fitted soap dischargepipe.

8. Apparatus according to claim l, comprising also a graining circuitincluding a third holding tank and a Vsecond circulating pumpcommunicating with the upper l and lower portions of said third tank, afeed pipe leading from said discharge line of the first circuit into thegraining circuit between said-second pump and said lower portion of thethird tank, a salt solution feed line leading into the graining circuit4between said second pump and 20 said lower tank portion, a centrifugalseparator, a discharge pipe from the graining circuit leading to theseparator, a soap discharge pipe and an impurity discharge pipe leadingfrom the separator, a fitting circuit to which said last soap dischargepipe leads and including a circulation pump, a heater and a holding tankconnected in the order mentioned, reckoned in the direction of iiowthrough said fitting circuit, a lye and salt solution supply pipeconnected to the fitting circuit, said supply pipe and soap dischargepipe being .connected to the fitting circuit between the holding tankand the pump therein, a second centrifugal separator, a pipe leading tosaid last separator from the fitting circuit in front of the pumptherein, niger and soap discharge pipes leading from said lastseparator, and a pipe connecting said niger discharge pipe to one ofsaid circuits in advance of the fitting circuit.

9. Apparatus according to claim l, comprising also a graining circuitincluding a third holding tank and a second circulating pumpcommunicating with the upper and lower portions of said third tank, afeed pipe leading from said discharge line of the first circuit into thegraining circuit between said second pump and said lower portion of thethird tank, a salt solution feed line leading into the graining circuitbetween said second pump and 4,5 said lower tank portion, a centrifugalseparator, a discharge pipe from the graining circuit leading to theseparator, a soap discharge pipe and an impurity discharge pipe leadingfrom the separator, a fitting circuit to which said last soap dischargepipe leads and including a circulation pump, a heater and a holding tankconnected in the order mentioned, reckoned in the direction of flowthrough said fitting circuit, a lye and salt solution supply pipeconnected to the fitting circuit, said supply pipe and soap dischargepipe being connected to the fitting circuit between the holding tank andthe pump therein, a second centrifugal separator, an interconnectingpipe leading to said last separator from the fitting circuit in front ofthe pump therein, a pipe leading from said last separator for dischargeof fitted soap, a second 5() fitting circuit including a circulationpump, a heater and a holding tank connected in the order mentioned,reckoned in the direction of fiow therethrough, a supply pipe forfeeding lye, salt solution and water into the second fitting circuit,said last supply pipe and fitted soap dis- 55 charge pipe beingconnected to the second fitting circuit between the holding tank and thepump therein, a third centrifugal separator, and an interconnecting pipeleading to the third separator from the second fitting circuit betweenthe tank and pump thereof but in front of said fitted soap dischargepipe, the third separator having separate discharge pipes for niger andsoap, and a pipe connecting said last niger discharge pipe to the firstfitting circuit.

l0. Apparatus according to claim 6, .comprising also 75 a feedpump insaid pipe leading to the last separator from the fitting circuit.

l1. Apparatus according to claim 7, comprising also a feed pump in saidpipe leading to the third separator from the second fitting circuit.

l2. Apparatus according to claim l, comprising also a graining circuitincluding a third holding tank and a second circulating pumpcommunicating with the upper and lower portions of said third tank, afeed pipe leading from said discharge line of the first circuit into thegraining circuit between said second pump and said lower portion of thethird tank, a salt solution feed line leading into the graining circuitbetween said second pump and said lower tank portion, a centrifugalseparator, a discharge pipe from the graining circuit leading to theseparator, a soap discharge pipe and an impurity discharge pipe leadingfrom the separator, a fitting circuit to which said last soap dischargepipe leads and including a circulation pump, a heater and a holding tankconnected in the order mentioned, reckoned in the direction of fiowthrough said fitting circuit, a lye and salt solution supply pipeconnected to the fitting circuit, said supply pipe and soap dischargepipe being connected to the fitting circuit between the holding tank andthe pump therein, a second centrifugal separator, a pipe leading to saidlast separator from the fitting circuit, the fitting circuit, secondseparator and interconnecting pipe forming a closed system adapted foroperation at super-atmospheric pressure, a feed pump and a tank in saidsoap discharge pipe leading from the first separator to the fittingcircuit, said lye and salt solution pipe also communicating with saidlast tank, and a dosing device in said last pipe.

13. Apparatus according to claim 1, comprising also a graining circuitincluding a third holding tank and a second circulating pumpcommunicating with the upper and lower portions of said third tank, afeed pipe leading from said discharge line of the first circuit into thegraining circuit between said second pump and said lower portion of thethird tank, a salt solution feed line leading into the graining circuitbetween said second pump and said lower tank portion, a centrifugalseparator, a discharge pipe from the graining circuit leading to theseparator, a soap discharge pipe and an impurity discharge pipe leadingfrom the separator, a fitting circuit to which said last soap dischargepipe leads and including a circulation pump, a heater and a holding tankconnected in the order mentioned, reckoned in the direction of fiowthrough said fitting circuit, a lye and salt solution supply pipeconnected to the fitting circuit, said supply pipe and soap dischargepipe being connected to the fitting circuit between the holding tank andthe pump therein, a second centrifugal separator, and interconnectingpipe leading to said last separator from the fitting circuit in front ofthe pump therein, a pipe leading from said last separator for dischargeof fitted soap, a heater and a holding tank connected in the ordermentioned, reckoned in the direction of iiow therethrough, a supply pipefor feeding lye, salt solution and water into the second fittingcircuit, said last supply pipe and fitted soap discharge pipe beingconnected to the second fitting circuit between the holding tank and thepump therein, a third centrifugal separator, and an interconnecting pipeleading to the third separator from the'second fitting circuit betweenthe tank and pump thereof but in front of said fitted soap dischargepipe, said fitting circuits, second and third separators andinterconnecting pipes forming a closed system adapted for operation atsuper-atmospheric pressure, a feed pump and a tank in each of said soapdischarge pipes leading to the fitting circuits, said supply pipes tothe first and second fitting circuits leading thereto, respectively, byway of the tanks in the soap discharge pipes leading to the first andsecond fitting circuits, and a dosing device in each of said supplypipes.

14. Apparatus according to claim 13, comprising also a niger dischargepipe and a soap discharge pipe leading from said third separator, and apipe connecting said last niger discharge pipe to the tank in said soapdischarge pipe leading to the rst tting circuit.

15. Apparatus according to claim 1, comprising also a. heater located insaid circuit between the mixer and the second holding tank.

References Cited in the file of this patent UNITED STATES PATENTS SouleJuly 27, 1926 Scott et al. Nov. 3, 1942 Pyzel Oct. 26, 1943 Bodman etal. Oct. 23, 1951

1. APPARATUS FOR EFFECING CHEMICAL REACTION BETWEEN TWO REACTANTS, WHICHCOMPRISES PARTS INCLUDING A CIRCULATION PUMP, A FIRST HOLDING TANK, AMIXER, AND A SECOND HOLDING TANK, PIPING CONNECTING ALL OF SAID PARTS INSERIES IN A CLOSED FIRST CIRCUIT IN THE ORDER MENTIONED, RECKONED IN THEDIRECTION OF FLOW OF MATERIAL THROUGH THE CIRCUIT, A FIRST REACTANT FEEDLINE LEADING INTO THE CIRCUIT AT A POINT THROUGH WHICH SAID MATERIALFLOWS ON ITS WAY FROM THE SECOND TANK TO THE FIRST TANK, A SECONDREACTANT FEED LINE LEADING INTO THE CIRCUIT AT A POINT THROUGH WHICHSAID MATERIAL FLOWS ON ITS WAY FROM THE FIRST TANK TO THE MIXER, AND ADISCHARGE LINE LEADING FROM THE CIRCUIT AT A POINT THROUGH WHICH SAIDMATERIAL PASSES ON ITS WAY FROM THE SECOND HOLDING TANK TO SAID FIRSTREACTANT FEED LINE.